There have been numerous attempts to enhance the storage stability of peroxycarboxylic acids. It is well known to enhance the storage stability of peroxycarboxylic acids by encapsulating or coating them. U.S. Pat. No. 4,288,388, McCrudden et al (Sept. 8, 1981), discloses aromatic peroxycarboxylic acids compounds containing at least three peroxycarboxylic acid groups. It is stated that such compounds can be desensitized by admixing, granulating or coating them with a diluent such as magnesium sulfate. Desensitizing is reducing the explosiveness of the compounds.
U.S. Pat. No. 4,287,135, Stober et al (Sept. 1, 1981), discloses that diperoxyalkanedioic acids and aromatic peroxycarboxylic acids can be prepared by reacting a dialkanoic acid or an aromatic carboxylic acid with hydrogen peroxide and sulfuric acid and then producing a desensitizing agent for the peroxycarboxylic acid in situ by adding alkali metal hydroxide, alkali metal aluminate or an alkaline earth metal hydroxide so that the filtrate is free of sulfuric acid. It is stated that the resulting salt coats the peracid and thus the product is desensitized and stable in storage.
U.S. Pat. No. 4,094,808, Stewart et al (June 13, 1978), discloses an organic peroxycarboxylic acid formulation in the form of an encapsulated core comprising particles of a solid organic peroxycarboxylic acid in admixture with particles of a material substantially more water-soluble than the organic peroxycarboxylic acid that is utilized as a dispersing agent. The core is completely encapsulated with a hydratable inorganic salt in less than the maximum state of hydration; for example, MgSO.sub.4.H.sub.2 O.
U.S. Pat. No. 3,639,285, Nielsen (Feb. 1, 1972), discloses that the stability of monoperoxyphthalic acids or diperoxyphthalic acids and mixtures thereof can be substantially improved by incorporating therewith an alkali metal or an alkaline earth metal salt of an acid having an ionization constant of the first hydrogen at 25.degree. C. of at least 1.times.10.sup.-3 ; for example, magnesium sulfate.
It is known that the magnesium salt of a carboxylic acid containing a peroxycarboxylic acid group is stable. U.S. Pat. No. 4,385,008, Hignet (May 24, 1983), discloses in solid form the magnesium salt of certain aromatic, cycloaliphatic or conjugated aliphatic compounds containing a peroxycarboxylic acid group and a carboxylate group. It is clearly pointed out that the magnesium salt formed is that of the carboxylic acid group only and that the peroxycarboxyl group remains in acid form. It is stated that such compounds have excellent storage stability.
Some salts of peroxycarboxylic acids in solid form are known. U.S. Pat. No. 2,957,935, Wildl et al (Oct. 25, 1960), discloses a process to prepare mercury peroxycarboxylates.
U.S. Pat. No. 2,861,100, Humber (Nov. 18, 1958), discloses a process of the preparation and isolation of the anhydrous salts of a saturated aliphatic peroxycarboxylic acid.
German Pat. No. 1,099,538, D'Ans et al (published Feb. 16, 1961), discloses a process for the production of anhydrous, solid or dissolved, alkali metal or alkaline earth salts of organic hydroperoxides. See also: J. D'Ans and H. Gold, Chem. Ber., 92, 2559 (1959).
U.S. Pat. No. 3,384,596, Moyer (May 21, 1968) and British Pat. No. 1,222,437, Moyer (Apr. 16, 1968) discloses an aqueous bleaching composition of 3-chloroperoxybenzoic acid having a pH of at least 9 with either calcium or magnesium ion employed at a ratio to the peroxycarboxylic acid of 0.5 to 1.0 is improved bleaching activity over similar aqueous bleaching compositions which lack the calcium or magnesium ions. It is alleged that the effect is not due to stabilization (Col. 2, lines 61-66).
U.S. Pat. No. 3,494,787, Lund and Nielsen (Feb. 10, 1970) discloses storage stable diperoxyphthalic acids encapsulated in a protective coating of a hydrated salt such as magnesium sulfate. It is clearly pointed out that the particles so formed consist of a core of diperoxyphthalic acid bleaching agent surrounded by a layer or shell of inorganic, hydrated, water soluble salt.
U.S. Pat. No. 3,494,786, Nielson (Feb. 10, 1970) discloses granulated compositions of peroxyphthalic acid cores encapsulated in protective coatings of hydrated magnesium sulfate.
U.S. Pat. No. 3,510,512, Jourdan-Laforte (May 5, 1970) discloses a method for obtaining stable monoperoxyphthalic acid from the reaction of phthalic anhydride and hydrogen peroxide in a halogenated hydrocarbon solvent with an alkaline catalyst.
U.S. Pat. No. 3,235,584, Blumbergs (Feb. 15, 1966) discloses a process for producing peroxycarboxylic acids from organic acid halides and aqueous alkaline hydrogen peroxide solutions. Either alkali metal peroxides or alkaline earth metal peroxides are used to form aqueous solutions of the alkali metal or alkaline earth metal salt of the peroxycarboxylic acid. The salts are acidified to form the peroxycarboxylic acid.
U.S. Pat. No. 4,321,301, Brichard and Colery (Mar. 23, 1982) discloses a process for stabilizing particles of peroxygenated compounds, including peroxycarboxylic acids, by coating with a boron compound. These particles are said to lose less than 15% active oxygen after two weeks when admixed with base detergent powder.
U.S. Pat. No. 3,847,830, Williams et al (Nov. 12, 1974) discloses a peroxygen containing composition enveloped in a water dispersible layer for improved storage stability. Suitable water dispersible layers are composed of fatty acids, glycerol esters, and alkanolamide derivatives.
European Patent Application No. 0030759, Brichard (published Mar. 12, 1980) discloses a process for stabilizing peroxygen containing particles, including peroxycarboxylic acids, by coating them in a fluid bed with waxes such as fatty acid esters and amides, polyethyleneglycol, glycerol, alcohols, and various polymers.
U.S. Pat. No. 2,838,459, Sprout (June 10, 1958) discloses the stabilization of solutions containing peroxygen compounds using a stabilizer additive which liberates magnesium ions in alkaline aqueous solutions. For example, magnesium sulfate, chloride, and silicate may be used.
U.S. Pat. No. 4,128,495, McCrudden (Dec. 5, 1970) discloses bleaching compositions of phthaloyl peroxides which are desensitized by intimate contact with a diluent, e.g., magnesium sulfate.
Japanese Kokai Tokkyo Koho No. 80 445,654, Application No. 78/119,481, Takao et al (Mar. 31, 1980) discloses the stabilization of liquid peroxycarboxylic acids with thiocyanate salts, e.g., sodium, potassium, ammonium, or magnesium thiocyanate.
U.S. Pat. No. 2,670,266 (Feb. 23, 1954) discloses alkali metal persalts useful as bleaching agents.
British Patent No. 656,938 (Sept. 5, 1951) discloses salts of peroxycarboxylic acids which are useful in shrinkproofing wool.
European Patent Application No. 74,730, Millar (published Mar. 23, 1983) discloses a method for granulating magnesium salts of various peroxycarboxylic acid carboxylates described in European Patent application No. 27693 (U.S. Pat. No. 4,385,008, Hignet, May 24, 1983).
Belgian Patent No. 560,389 (Sept. 3, 1956) discloses a stabilized mixture of organic peroxycarboxylic acid and mineral salts capable of absorbing water as water of crystallization.
Masao Okubo et al, Bull. Chem. Soc. Jap., 44, 1365-1368 (1971) discloses a complex containing magnesium, bromine, and benzoyl peroxide.
Additional disclosures include G. Sosnovsky and J. Brown, Chem. Rev., 66, 329 (1966) and G. A. Razuvaev et al in "Organic Peroxides", Vol. 111, D. Swern, Ed., Wiley-Interscience, New York (1978), Ch. 3, p. 141.
All of the above patents and literature are incorporated herein by reference.